Currently, there are image forming apparatuses such as a multi-function peripheral (hereinafter, referred to as an “MFP”) and a printer. The image forming apparatus includes a fixing device. The fixing device heats a conductive layer of a fixing belt by using an electromagnetic induction heating method (hereinafter, referred to as an “IH” method). The fixing device fixes a toner image to a recording medium with heat of the fixing belt. For example, the fixing device includes an auxiliary heat generation section which opposes an induced current generation section with the fixing belt interposed therebetween. The induced current generation section generates magnetic flux when a high frequency current is applied thereto from an inverter driving circuit. The inverter driving circuit includes an insulated gate bipolar transistor (IGBT) element. The auxiliary heat generation section concentrates magnetic flux during electromagnetic induction heating so as to increase an amount of generated heat in the fixing belt. The auxiliary heat generation section may excessively increase a temperature of the IGBT element and thus the IGBT element may be damaged when a high output is continued, such as during continuous sheet passing or during warming-up.